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Abstract:

The present application discloses novel endohedral fullerenes having
enclosed therein one or more ozone molecules, e.g. fullerenes selected
from C60-fullerene (Buckminsterfullerene), C70-fullerene,
C76-fullerene, C78-fullerene, C82-fullerene,
C84-fullerene, and C120-fullerene. The application further
discloses a composition comprising the endohedral fullerene and a carrier
material, e.g. where the carrier material is a skin lotion, such as a
skin lotion comprising L-ascorbic acid or Vitamin E. Moreover, various
uses of the novel fullerenes are disclosed, e.g. for skin UV-protection;
in or on the surface of sun glasses; in or on the surface of window
glass; in or on the surface of textiles, fabrics, clothes, wood, paint,
paper, cushions, leather, hair-care products, and plants.

Claims:

1. An endohedral fullerene having enclosed therein one or more ozone
molecules.

2. The endohedral fullerene according to claim 1, which is selected from
C60-fullerene, C70-fullerene, C76-fullerene,
C78-fullerene, C82-fullerene, C84-fullerene, and
C120-fullerene.

3. A composition comprising the endohedral fullerene as defined claim 1,
and a carrier material.

4. The composition according to claim 3, wherein the carrier material is
a skin lotion.

5. The composition according to claim 4, wherein the skin lotion
comprises an antioxidant, such as at least one selected from L-ascorbic
acid and Vitamin E.

6. Use of an endohedral fullerene as defined in claim 1: a. for skin
UV-protection; b. in or on the surface of sun glasses; c. in or on the
surface of glass; d. in or on the surface of i. textiles, ii. fabrics,
iii. clothes, iv. wood, v. paint, vi. paper, vii. cushions, viii.
leather, ix. hair-care products, or x. plants.

7. A method for the preparation of an endohedral fullerene as defined in
claim 1, the method comprising the principal steps: (a) providing an
endohedral fullerenes having enclosed therein one dioxygen molecule, (b)
bombarding the fullerene with oxygen ions, whereby the dioxygen molecule
is converted into an ozone molecule.

Description:

FIELD OF THE INVENTION

[0001] The present invention relates to novel principles in the form of
endohedral fullerenes having enclosed therein one or more ozone
molecules, in particular one ozone molecule, (i.e. "fullerene-entrapped
ozone") which are suggested for use as efficient UV-absorbing agents. The
molecular structures provide the benefits of ozone as a UV-absorbing
agent while at the same time leaving the otherwise reactive species,
ozone, in an environment wherein it is essentially non-reactive.

BACKGROUND OF THE INVENTION

[0002] Protection against the UV-radiation is an increasing issue in
Denmark as the prognosis shows that the intensity of the radiation and
the number of skin cancer patients will escalate in line with the
dilution of the ozone layer. Over a period of 25 years incidents of skin
cancer will grow with 20%. Skin cancer is just one out of many adverse
effect of the UV-radiation. The problem with absent protection against
the UV-radiation is not only a national concern but a global problem,
e.g. in New Zealand where incidences of skin cancer are expected to
increase by 50% within the next 10 years.

[0003] Ozone (or trioxygen, (O3)) is a triatomic molecule, consisting
of three oxygen atoms. It is an allotrope of oxygen that is much less
stable than the diatomic O2. Ground-level ozone is an air pollutant
with harmful effects on the respiratory systems of animals. The ozone
layer in the upper atmosphere filters potentially damaging ultraviolet
light from reaching the Earth's surface.

[0005] The atomic oxygen produced immediately reacts with other oxygen
molecules to reform ozone:

O2+O.+M→O3+M

where "M" denotes the third body that carries off the excess energy of
the reaction. In this way, the chemical energy released when 0 and
O2 combine is converted into kinetic energy of molecular motion. The
overall effect is to convert penetrating UV light into heat, without any
net loss of ozone. This cycle keeps the ozone layer in a stable balance
while protecting the lower atmosphere from UV radiation, which is harmful
to most living beings. It is also one of two major sources of heat in the
stratosphere (the other being the kinetic energy released when O2 is
photolyzed into O atoms).

[0006] Curl, Kroto and Smalley (Kroto, et al. Nature, Vol 318, p. 162,
1985) were the first to make and identify C60-fullerenes
("buckyballs") in the laboratory. One of the most common routes towards
the native fullerenes involves the heating of graphite rods to a high
temperature by passing an electric current between them, and then
separating the fullerenes from other carbon compounds in the resulting
soot (fine carbon particles). Typically, about 75% of the crystals are
C60-fullerene molecules, 23% are C70-fullerene molecules and
the remains comprise larger molecules. Later on, various other groups
have been able to prepare larger quantities of fullerenes, also on a
commercial scale, and nowadays C60-, C70-, C76-,
C78-, C82- and C84-fullerenes and a variety of derivatives
are available from commercial sources, just as the production price has
been dramatically reduced. Birkett has prepared an excellent review of
the chemistry of fullerenes (http://www.rsc.org/ej/IC/1998/ic094055.pdf).

[0008] It is an object of embodiments of the invention to provide new
molecular structures which render it possible to utilize the beneficial
properties of ozone with respect to UV-absorption and at the same
eliminate the undesirable properties of ozone. Such new molecular
structures may have applications within various technical fields, e.g. in
sun protection lotions (skin lotions), sunscreens, anti-aging products,
etc., sun glasses, textiles, sun screens, wind screens, etc.

SUMMARY OF THE INVENTION

[0009] In order to solve the above-mentioned problems, the present
invention provides an endohedral fullerene having enclosed therein one or
more ozone molecules, in particular one ozone molecule.

[0010] Moreover, the present invention is a composition comprising the
endohedral fullerene as defined herein, and a carrier material, e.g. a
skin lotion.

[0011] Furthermore, the invention provides the use of an endohedral
fullerene as defined herein: for skin UV-protection; in or on the surface
of sun glasses; in or on the surface of window glass; in or on the
surface of textiles, fabrics, clothes, wood, paint, paper, cushions,
leather, hair-care products, and plants.

[0012] The novel endohedral fullerenes facilitate the practical and daily
day use of the ozone molecule which alone and in particular in
combination with fullerenes is an excellent absorber of ultra violet
light, e.g. to protect against the UV light from the sun, for example so
as to construct an optimized sun-blocker with the ability to absorb UVA-,
UVB-, UVC-, UVD-radiation.

BRIEF DESCRIPTION OF THE FIGURES

[0013] FIG. 1 illustrates the introduction of ozone molecules in a
fullerene (here a C60-fullerene). The Figure is created as a result
of a computer simulation using the Program Gaussian-09
(www.gaussian.com).

[0014] FIG. 2 illustrates the action of the fullerene-entrapped ozone as a
UV-absorbing molecular structure.

[0019] FIG. 7 illustrates the size reduction of the orifice of
O2@C5 by removal the sulfur atom.

[0020] FIG. 8 illustrates the reduction of O2@C4 to
O2@C7.

[0021] FIG. 9 illustrates dioxygen inside C60, O2@C60.

[0022] FIG. 10 illustrates the schematic of the beam machine for
implanting ions in fullerenes.

[0023] FIG. 11 illustrates the schematics of the production of
O3@C60 by ion implantation.

DETAILED DISCLOSURE OF THE INVENTION

[0024] As mentioned above, the present invention provides an endohedral
fullerene having enclosed therein one or more ozone molecules, in
particular one ozone molecule.

DEFINITIONS

[0025] In the present context, the term "fullerene" is intended to
encompass a variety of molecules composed entirely of carbon, in the form
of hollow structures, such as spheres, ellipsoids, tubes, etc. In the
present context, the structures must be such that they can entrap at
least one ozone molecule, hence the structures much include at least one
closed cavity which provides sufficient space for at least one ozone
molecule to be entrapped therein.

[0027] One of the best known fullerenes is the Buckminsterfullerene (IUPAC
name (C60-Ih)[5,6]fullerene), commonly referred to as "C60" or
the "Buckyball".

[0028] Unless explicitly specified otherwise, the terms "fullerene" and
"one or more fullerenes" are intended to encompass a single type of
fullerene (e.g. C60-fullerene) as well as a combination of two or
more types of fullerenes (e.g. a mixture of C60-, C70-, . . .
C84-, C120-fullerenes, etc.)

[0029] Moreover, "fullerenes" in the present context are also intended to
encompass derivatives having covalently linked thereto various groups on
the outside of the molecular structure. Examples hereof are fullerenes
carrying a plurality of hydroxyl groups. Such derivatized fullerenes,
e.g. those derivatized with hydroxyl groups, are rendered more
hydrophilic than the native fullerene (which notoriously is quite
hydrophobic) and are therefore more easily incorporated in hydrophilic
material, e.g. skin lotions.

[0030] The term "endohedral fullerene" refers to fullerenes that have
additional atoms, molecules, ions, or clusters enclosed within their
inner spheres. In the present context, such endohedral fullerenes have
enclosed therein at least one ozone molecule, but possibly two or more
ozone molecules.

[0031] Preparation of Endohedral Fullerenes Having Enclosed Therein One or
More Ozone Molecules

[0032] The endohedral fullerenes having enclosed therein one or more ozone
molecules, in particular one ozone molecule, may be prepared in
accordance with the known methodologies for introducing one or more atoms
or small molecules into fullerenes, e.g. as described in the following
(Methods A and B).

[0033] Method A

[0034] By this method, the ozone molecules are introduced in the fullerene
after the fullerene structure has been formed, and the introduction may
be accomplished in accordance with one or more of the following variants:

[0035] In the first variant of method A, (1) an orifice in the fullerene
structure is opened, (2) the orifice is enlarged, (3) the ozone
molecule(s) (and possibly also dioxygen molecules) are introduce in the
structure via the orifice, (4) the orifice is reduced in size, and,
finally, (5) the fullerene is reconstructed by complete closure of the
orifice. This method is described in general terms in "Method", in
Michihisa Murata, "100% Encapsulation of a Hydrogen Molecule into an
Open-Cage Fullerene Derivative and Gas-Phase Generation of H2@C60",
Institute for Chemical Research, Kyoto University, 2006,
http://repository.kulib.
kyoto-u.ac.jp/dspace/bitstream/2433/64942/1/D_Murata_Michihisa.pdf.

[0036] Within this variant of Method A, it is possible to introduce mainly
dioxygen molecules (in particular one dioxygen molecule per fullerene) in
the structure via the orifice (step (3)). Subsequently, the orifice is
reduced in size (step (4)) and the fullerene is reconstructed by complete
closure of the orifice (step (5)).

[0037] Finally, a third oxygen atom is introduced into the fullerene
structure, e.g. by bombarding a sample of the fullerenes with oxygen
ions. A beam machine as the one illustrated in FIG. 10 may suitably be
used.

[0038] One advantage of this method variant is that the reactivity of
ozone during insertion thereof in the fullerene through the orifice is
avoided (steps (4) and (5)). In this way, one extra oxygen atom is
introduced into the fullerenes structure which also has enclosed therein
the dioxygen molecule. By the reaction O2+O. in the fullerene ozone
(O3) is formed.

[0039] Hence, in a currently very interesting embodiment, the endohedral
fullerene having enclosed therein one or more ozone molecules, in
particular one ozone molecule, is prepared by the following method:

(1) an orifice in the fullerene structure is opened, (2) the orifice is
enlarged, (3) one or more dioxygen molecule(s) (in particular one
dioxygen molecule) are introduce in the structure via the orifice, (4)
the orifice is reduced in size, (5) the fullerene is reconstructed by
complete closure of the orifice, (6) the fullerene is bombarded with
oxygen ions, whereby the dioxygen molecule is converted into an ozone
molecule.

[0040] In view hereof, the present invention also provides an endohedral
fullerene having enclosed therein one or more dioxygen molecules, in
particular one dioxygen molecule. Such fullerenes may be useful in the
preparation of the endohedral fullerenes having enclosed therein one or
more ozone molecules, in particular one ozone molecule.

[0041] Hence, in a further embodiment, the endohedral fullerene having
enclosed therein one or more ozone molecules, in particular one ozone
molecule, is prepared by the following method:

(a) providing an endohedral fullerene having enclosed therein one or more
dioxygen molecules, in particular one dioxygen molecule, (b) bombarding
the fullerene with oxygen ions, whereby the dioxygen molecule is
converted into an ozone molecule.

[0042] The second variant of Method A requires that ozone molecules (or
alternatively dioxygen molecules) are ionized. The ozone molecules (and
possibly also dioxygen molecules) are initially ionized. The ionized
ozone molecules are accelerated in an electrical field so as to form a
beam of ionized ozone which is then allowed to come in contact with a
sample of the fullerene (e.g. a thin solid sample or as a gas cloud) (see
also the Experimentals section).

[0043] Hence, the present invention also provides a method for the
preparation of endohedral fullerenes having enclosed therein one or more
ozone molecules, in particular one ozone molecule, the method comprising
the principal steps: [0044] providing a sample comprising one or more
fullerenes; [0045] ionizing ozone and/or dioxygen and accelerating the
ionized ozone and/or dioxygen in an electrical field so as to provide a
beam of ionized ozone and/or dioxygen; [0046] allowing the beam of
ionized ozone and/or dioxygen to collide with said a sample of one or
more fullerenes; and collecting the fullerene(s) having in the interior
thereof one or more ozone and/or dioxygen molecules, in particular one
ozone or dioxygen molecule, and if necessary, converting dioxygen
molecules to form at least one ozone molecule.

[0047] In the first step, the sample of the one or more fullerenes should
be presented in such a manner, e.g. in a gas cloud, or in a thin layer of
only 1-10 molecules, in particular 1-5 molecules, such that a majority of
molecules are directly accessible to the beam of ionized ozone. The
sample is typically arranged in a vacuum chamber so as to become suitably
accessible for the beam of the ionized ozone (see below).

[0048] The ionization and acceleration of the ozone in the second step is
accomplished by conventional method using conventional equipment.

[0049] The third step of allowing the beam of ionized ozone to collide
with the sample of the one or more fullerenes is also accomplished in
conventional equipment.

[0050] Finally, the fullerene(s) having in the interior thereof one or
more ozone molecules, in particular one ozone molecule, is/are collected
and suitably stored before application, preferably stored in an inert
atmosphere.

[0051] In a third variant of Method A, the one or more ozone molecules
(and/or dioxygen molecules), in particular one ozone or dioxygen
molecule, are introduced into the interior of the fullerene by means of a
high pressure. Hence in this alternative method the principal steps of
the preparation are: [0052] providing a sample comprising one or more
fullerenes; [0053] arranging the one or more fullerenes in a chamber
having therein pressurized ozone (or dioxygen); and [0054] collecting the
fullerene having in the interior thereof one or more ozone molecules, in
particular one ozone molecule (or dioxygen molecule).

[0055] Method B

[0056] In this method, the ozone molecules (and possibly also dioxygen
molecules) are entrapped in the fullerene as the fullerene is prepared.
The preparation of the endohedral materials entrapped ozone molecules is
accomplished in two possible ways, cf. the two following variants.

[0057] In a first variant of Method B, the fullerene is prepared by
striking an arc between two graphite electrodes in the presence of ozone
gas. A mixture of fullerenes is prepared, some of which have enclosed
therein one or more ozone molecules, in particular one ozone molecule.

[0058] In a second variant of Method B, the fullerene is prepared by
bombarding a graphite target with a powerful laser in the presence of
ozone gas. A mixture of fullerenes is prepared, some of which have
enclosed therein one or more ozone molecules, in particular one ozone
molecule.

[0059] Even though C60-fullerene is the most common fullerene, it is
typically advantageous to utilize even larger fullerenes in the methods
and for the compounds in order to obtain a higher abundance of ozone
molecules within the fullerene. Hence, although the fullerene are
typically selected from C60-fullerene, C70-fullerene,
C76-fullerene, C78-fullerene, C82-fullerene,
C84-fullerene, and C120-fullerene, it is believed to be even
more advantageous to select the fullerenes from C70-fullerene,
C76-fullerene, C78-fullerene, C84-fullerene, and
C120-fullerene, or even more advantageous from C76-fullerene,
C78-fullerene, C84-fullerene, and C120-fullerene.

[0060] It should be understood that the efficiency of the above methods
might be less than 100% so that a fraction of the fullerene molecules
might not have ozone molecules in the interior thereof. Due to the
excellent properties of the endohedral fullerenes having enclosed therein
one or more ozone molecules, in particular one ozone molecule, is it
still believed that such samples partly consisting of native fullerenes
and partly consisting of endohedral fullerenes (fullerene-entrapped
ozone) are of great value in various industrial fields (see further
below).

[0061] The actual number of ozone molecules and/or dioxygen molecules in a
sample of endohedral fullerenes can be determined by means of mass
spectrometry (see the "Experimentals" Section further below).

[0062] This being said, a sample of fullerenes (partly consisting of
native fullerenes and partly consisting of endohedral fullerenes
(fullerene-entrapped ozone or dioxygen)) may be enriched with respect to
the endohedral fullerenes by chromatographic means.

[0063] Purification (and enrichment) by chromatographic means is also
beneficial in order to remove carbon soot, because the above-mentioned
techniques typically produce a significant large amount of carbon soot in
addition to the desirable endohedral fullerenes.

SPECIFIC EMBODIMENTS OF THE INVENTION

[0064] The endohedral fullerenes of the invention are typically used in
combination with a carrier material.

[0065] In one embodiment, the carrier material is a skin lotion, a
sunscreen, an anti-aging product, etc. Preferably, the skin lotion
includes an antioxidant, such as at least one selected from L-ascorbic
acid and Vitamin E.

INDUSTRIAL APPLICATIONS

[0066] The initial rational behind the invention is to prepare suitable
new molecular structures which render it possible to utilize the
beneficial properties of ozone with respect to UV-absorption, in
particular with the aim of providing excellent UV-protection properties
to skin lotions.

[0067] The novel fullerene-entrapped ozone structures renders it possible
to provide an efficient UV-protection in that the fullerene as such is
capable of absorbing light in the UV-A range (400 nm-320 nm) and in that
the ozone is capable of absorbing light in the UV-B (320 nm-280 nm), UV-C
(280 nm-185 nm) and UV-D (185 nm-10 nm) ranges.

[0068] Hence, one interesting aspect of the present invention is a skin
lotion having included therein one or more fullerene molecules having in
the interior thereof one or more ozone molecules, in particular one ozone
molecule. Of course depending on the "load" of fullerene molecules in the
skin lotion and the "load" of ozone molecules in the interior of the
fullerene molecules, such a skin lotion can provide a close to 100%
protection against harmful UV-irradiation from the sun.

[0069] Among other interesting industrial applications can be mentioned
sun glasses either having the fullerene-entrapped ozone in a coating
layer, or--possibly more effective--having the fullerene-entrapped ozone
incorporated in the material (e.g. glass or polymer) constituting the
glasses. The same applies for contact lenses, which can be provided with
UV-absorbing properties by means of the fullerene-entrapped ozone.

[0070] Among other interesting industrial applications can be mentioned
glass (e.g. window glass, sun screens, wind screens) either having the
fullerene-entrapped ozone in a coating layer on the glass, or having the
fullerene-entrapped ozone incorporated in the glass as such.

[0071] Also interesting are various types of goods, e.g. textiles,
fabrics, clothes (such as bathing suits, e.g. for kids), wood (such as
garden equipment, panels, furniture, etc.), paint, paper (such as books,
out-door posters, magazines, news papers, photographs), cushions,
leather, hair-care products, plants, etc., the surface of which may be
provided with UV-absorbing properties by inclusion of fullerene-entrapped
ozone. Many more applications can be envisaged.

[0072] First the methodology of "molecular surgery" will be followed to
produce O2@C60. This procedure will consist of the following
steps: (1) opening an orifice on the C60 framework, (2) enlarging
the orifice, (3) putting O2 through the orifice, (4) reducing the
size of the orifice, and (5) finally reproducing the original C60
form by complete closure of the orifice.

(a) A purple solution of compound C1 (66 mg) in CCl4 (65 mL) in
a Pyrex flask is irradiated by a high-pressure mercury lamp (500 W) from
a distance of 20 cm for 6 h under air. The resulting brown solution is
evaporated and the residual black solid is dissolved in ODCB (3 mL). This
is then subjected to preparative HPLC using a Cosmosil 5PBB column (10
mm×250 mm) eluted with ODCB (flow rate, 2 mL min-1) this gives
three different open-cage fullerene derivatives C2 (40 mg, retention
time: 8.7 min), C3 (21 mg, retention time: 9.2 min), and C4 (1
mg, retention time: 9.1 min), after nine recycles, all as brown powders
(See FIG. 4). (b) To a heated and stirred solution of compound C2
(32 mg) and elemental sulfur (8 mg as S8) in ODCB (15 mL) is added
tetrakis(dimethylamino)ethylene (7.1 μL) at 180° C. under
argon. The solution is refluxed at 180° C. for 30 min then the
resulting dark red-brown solution is concentrated by evaporation to about
3 mL. This is then added to pentane (30 mL) with vigorous stirring to
give brown precipitates. The precipitates, collected by centrifuge, are
then dissolved in ODCB (2 mL). The resulting solution is subjected to
flash chromatography on silica gel eluted with toluene-ethyl acetate
(30:1) to give the preferred open-cage fullerene derivative C5 (25
mg) as a brown powder (See FIG. 5).

[0076] The prepared compound C5 will have an orifice, whose size is
5.64 Å along the long axis and 3.75 Å along the short axis,
leaving room enough for an O2 to come through, as the short axis of
this molecule is app. 3.0 Å, and it is thermally stable up to
250° C.

[0077] In order to gain insight into the feasibility of insertion of small
atoms or molecules through the orifice of 1, Murata et al. (in Michihisa
Murata, "100% Encapsulation of a Hydrogen Molecule into an Open-Cage
Fullerene Derivative and Gas-Phase Generation of H2@C60", Institute for
Chemical Research, Kyoto

[0078] University, 2006,
http://repository.kulib.kyoto-u.ac.jp/dspace/bitstream/2433/64942/1/D_Mur-
ata_Michihisa.pdf) performed calculations of the activation energies
required for insertion of He, Ne, H2, and Ar into the compound, and
the energies were calculated to be 19.0, 26.2, 30.1, and 97.8 kcal
mol-1. Using the Gaussian-09 software, the activation energy the
insertion of O3 into C60 was calculated to 136.8 kJ/mol (32.7
kcal mol-1), which is well within the range of the values calculated
by Murata et al.

[0079] Ad (3) Putting O2 Through the Orifice:

(a) A powder of open-cage fullerene C5 (775 mg) lightly wrapped in a
piece of aluminum foil is heated at 200° C. in an autoclave under
a high-pressure O2 gas (800 atm). After 8 h, the powder is recovered
by washing the aluminum foil with CS2 (See FIG. 6).

[0080] Ad (4) Reducing the Size of the Orifice:

(a) First an oxidation of the sulfide unit of O2@C5 is
conducted by m-chloroperbenzoic acid (MCPBA) to make the sulfur atom
readily removable. A mixture of O2@C5 (107 mg) and
m-chloroperbenzoic acid (34 mg) in toluene (200 mL) is stirred at room
temperature for 13 h under nitrogen. The solvent is then evaporated under
reduced pressure, and the residual brown solid washed twice with methanol
(50 mL) and dried under vacuum to give O2@C6 (106 mg) as a
brown solid (See FIG. 7). (b) A stirred solution of O2@C6 (52
mg) in benzene (150 mL) in a Pyrex-glass flask is irradiated with a
xenon-lamp (500 W) placed at the distance of 20 cm at room temperature
for 17 h under argon. After removal of the solvent under reduced
pressure, the residual brown solid is subjected to flash column
chromatography over silica gel. Elution with CS2-ethyl acetate
(30:1) gives O2@C4 (21 mg) as a brown solid (See FIG. 7).

[0081] Ad (5) Finally Reproducing the Original C60 Form by Complete
Closure of the Orifice:

(a) To a stirred suspension of zinc powder (299 mg) in dry
tetrahydrofuran (10 mL) is added titanium tetrachloride (250 μl) drop
by drop at 0° C. under argon, and the mixture is refluxed for 2 h.
A 1-mL portion of the resulting black slurry is added to a stirred
solution of O2@C4 (49 mg) in ODCB (7 mL) at room temperature
under argon. After heating at 80° C. for 2 h, the resulting
brownish purple solution is cooled to room temperature. Then the solution
is diluted with CS2 (20 mL), and the resulting solution is washed
with saturated aqueous solution of NaHCO3 (50 mL). The organic layer
is dried over MgSO4 and evaporated under reduced pressure to give a
residual brown solid, which is then subjected to flash column
chromatography over silica gel. Elution with CS2-ethyl acetate
(20:1) gives O2@C7 (42 mg) as a brown solid (See FIG. 8). (b) A
powder of O2@C7 (245 mg) lightly wrapped with a piece of
aluminum foil is placed in a glass tube (inner diameter 20 mm), which is
sealed under vacuum (1 mmHg) and heated with an electric furnace at
340° C. for 2 h. The resulting black solid is completely soluble
in CS2, and the solution is passed through a glass tube packed with
silica gel to afford O2@C60 as a brown solid. Analytically pure
O2@C60 can be obtained by separation of this product by the use
of HPLC on a preparative Cosmosil Buckyprep column (two directly
connected columns, 10 mm×250 mm, with toluene as a mobile phase;
flow rate, 4 mL min-1) after recycling for 20 times (total retention
time, 399 min) (See FIG. 9).

[0082] The final step in producing O3@C60 is to introduce the
remaining oxygen atom to the analytically pure O2@C60 obtained
from the above synthesis.

[0083] FIG. 10 shows a schematic of a beam machine. In the centre is a
cylinder, which rotates a few minutes per second. On one side of the
cylinder is an oven, which produces a beam of fullerenes, in this case
O2@C60. On the other side is an ion source. Oxygen ions are
made in ionization chamber, the rate of oxygen ions is controlled by
varying the filament current in the ionization chamber. The oxygen ions
are then drawn out of the chamber by an electric field, and are
accelerated and focused by a set of ion lenses. The ion beam is bent by
some angle to separate it from metastable atoms and VUV photons possibly
produced in the ionization chamber. It then hits the surface where a
small fraction of the oxygen enters an endohedral fullerene molecule and
is trapped there together with the O2 already enclosed and left to
form O3, see FIG. 11. Since the ions can penetrate the surface only
to a depth of only one or two molecules, the surface must be continuously
renewed. The rotation of the cylinder in the middle of the fullerene beam
does this. After several hours of running, the cylinder is removed from
the apparatus and the sample can be retrieved from the surface of the
cylinder.

Example 2

Computational Simulation

[0084] The feasibility of the inclusion of an ozone molecule into C60
has been verified by a computational simulation using the Gaussian-09
software (see also FIG. 1). The electronic structure calculations were
done using the program Gaussian-09 and the Hartree-Fock or Self
Consistent Field method. This assumes that the electrons go into a set of
orbitals, two per orbital, one with spin up and the other with spin down.
The simulation started with a crude approximation of each orbital,
calculated a more accurate approximation, and then put the electrons in,
starting with the orbitals of lowest energy. This process was repeated
until the orbitals no longer changed. Each orbital was described as a
combination of simple basis functions:
orbitalx=a1*f1+a2*f2+a3*f3+ . . . . The f's
are the basis functions, like a hydrogen-like orbital on a given atom in
the molecule. The calculation then varied all the a's to obtain the
lowest energy. The calculation was done with each nucleus held at a fixed
position. The program was set to calculate the force on each nucleus and
then move it to lower the total energy.

[0085] It then iterated until a minimum in energy was reached. Initially
the calculations were done for empty C60 and for free ozone.
Subsequently, ozone was put inside the C60, and the calculation was
continued. In the Hartree-Foch approximation, each electron essentially
sees the other electrons as a diffuse charge cloud rather than as a set
of point particles. The electrons were defined as being uncorrelated in
that the probability of finding one electron at a given position is
independent of where all the other electrons are located. It would be
possible to correct for this correlation error, but the calculations
would be more extensive. In the present case where there are two
molecules that are not bonded together, the correlation correction gives
an attractive force, decreasing the energy. Basically, correlation moves
the electrons in O3 away from those in C60, decreasing the
energy slightly. Including the correlation will decrease the
incorporation energy. Without the correlation, the incorporation energy
was found to 136.8 kJ/mol.

[0086] The bond length in free O3 is 1.197 Å, whereas the bond
length of ozone incorporated into C60 is 1.183 Å. The bond angle
of free O3 is 119.09 degrees, whereas the simulation shows a bond
angle of 116.6 degrees for the ozone incorporated into C60.

Example 3

Preparation of Endohedral Fullerenes Having Enclosed Therein One or More
Ozone Molecules (Method A, Second Variant)

[0087] Various methods for the preparation of endohedral fullerenes having
enclosed therein one or more ozone molecules, in particular one ozone
molecule, have been described above. In one of these methods a beam
machine (see Example 1 and FIG. 10) is used to directly produce
fullerenes having enclosed therein one or more ozone molecules.

[0088] An alternative approach, would be to first accelerate dioxygen in a
magnetic field, utilizing the magnetic properties of dioxygen, and this
way create a beam of dioxygen to hit the fullerenes. The fullerenes with
the trapped dioxygen will then afterwards enter the above mentioned
system and be hit by the created beam of ionized oxygen. This method
might increase the efficiency of the process and produce a higher rate of
fullerenes consisting ozone.

Example 4

Analysis of Samples of Endohedral Fullerenes Having Enclosed Therein One
or More Ozone Molecules

[0089] The number of ozone-molecules (or combination of ozone and dioxygen
molecules) enclosed in the fullerene molecules can be determined by
conventional mass- and NMR-spectrometry equipment.

[0090] Based on the intensity of the MS peaks of the native fullerene(s)
(if any) and the heavier constituents, the average "load" of ozone
(and--if relevant--dioxygen) in the fullerene(s) can easily be
calculated.